THE disturbing cause of the massive wildfires that have blazed through New Jersey has been uncovered, according to officials.

Joseph Kling, 19, has been arrested and accused of sparking the blaze that torched 15,000 acres in the Pine Barrens with a now-devastating mistake.

Kling, who is from Ocean Township, about an hour south of New York City, allegedly started the tragedy by not properly putting out his bonfire.

According to the Ocean County Prosecutor’s Office, King started the fire in the Forked River Mountains Wilderness Area with wooden pallets.

By Tuesday morning at around 10 am, officials spotted a cloud of smoke erupting from the area and discovered a blaze was spreading.

In the three days the fire has burned, around 15,000 acres in Ocean County have been reduced to a crisp, and thousands have been forced to evacuate.

The blaze closed roads and businesses, and destroyed at least one commercial building, according to ABC affiliate WCAU.

Officials fear this could be the largest wildfire in New Jersey in the past 20 years.

As of Thursday morning, the wildfire had been contained by about 50%.

A months-long drought and rising temperatures created perfect conditions for the fire to spread through the heavily wooded Pine Barrens.

The one million-acre forest is mainly uninhabited, but officials have warned that residential areas in America’s most densely populated state could be at risk, the Associated Press reported.

King has been arrested and charged with arson.

He looked serious in a straight-faced mugshot taken after he was cuffed.